where the transport coefficients are the conductivity tensor \(\hat{\sigma }\)  or the mobility tensor \(\hat{\eta }\) . In two dimensions and for isotropic material, the mobility tensor is defined by Onsager relations [1]}:
\(\hat{\eta } =\begin{pmatrix}\eta & \eta _H \\-\eta _H & \eta \end{pmatrix}= \eta \begin{pmatrix}1 & \theta _H \\-\theta _H & 1\end{pmatrix}\quad \text{ with } \quad \theta _H = \frac{\eta _H}{\eta },\) 
